This invention relates to a facsimile receiver and more particularly to a continuously moving device carrying a printing bar.
In this type of apparatus, the printing takes place generally on electrolytic paper. It results from the passage of current between the printing bar and a helix arranged across the paper. The helix is supported by a rotating drum and its movement relative to the printing bar ensures the scanning of the paper.
The present invention is applied to a facsimile receiver having a chassis carrying a drum provided with a printing helix; a printing bar arranged between a supply roller and a drive roller; a guide roller for guiding a web of paper to be printed between the drum and the printing bar; a support for the printing bar and a pressure-roller for pressing the paper web against the drive roller. The chassis is pivotally mounted about an axis parallel to the axis of the drum so as to be displaceable between two positions, a first position in which the web of paper is held against the guide roller, between the drum and the printing bar, and between the drive roller and the presser-roller, and a second position giving free access to the supply roller and to the printing bar, thereby facilitating replacement of the paper roll and printing bar.
With such an apparatus, in order to avoid the risk of damaging the paper, the printing bar is only in contact with the paper, and the paper with the helix, during the actual time of transmission. Generally, with this type of apparatus, an electromagnet is used to automatically place the printing bar, the paper, and the helix into contact with each other, but this has the disadvantage of requiring the electromagnet coil to be continuously energized. Furthermore, in the case of coil failure, the various elements are not placed in contact with each other as required.
Preferably, in accordance with the present invention, a locking finger is supported by a locking lever articulated about an axis and provided with a spring tending to return the finger to the control shaft and against a stop, the axis of the finger being arranged parallel to the control shaft. This serves to maintain the chassis in its first position, whereby the printing bar is disposed in contact with the paper and the paper in contact with the helix. Furthermore, the locking finger may cooperate with a nib arranged at the end of the locking lever.